refactor: hard-fork GSD -> MSD (Make Software Done)

Mechanical rename produced by scripts/msd-rename.cjs: gsd/Gsd/GSD -> msd/Msd/MSD
across contents and paths, upstream package/repo coordinates -> @golem15/msd-core
and golem15com/msd-core. Deep links into upstream history, sibling upstream
packages, the GSD-2 import feature, CHANGELOG.md and .changeset/ are kept as-is.

Hand edits on top: MSD block-letter banner and logos, LICENSE copyright line,
package/plugin identity, regenerated lockfile, install-tree fixtures, derived
registries and benchmark baseline; migration checksum baseline re-locked
(MSD keeps its own install state, so no install had applied the old sums);
sort-order and regex-escaped expectations in tests adjusted.

src/spec-section.cts

@@ -12,7 +12,7 @@
  *
  * Authored as strict TypeScript (`src/spec-section.cts`) and compiled by
  * `tsc -p tsconfig.build.json` to the gitignored runtime artifact
- * `gsd-core/bin/lib/spec-section.cjs`. Do NOT hand-write the `.cjs`; it is emitted. Tests
+ * `msd-core/bin/lib/spec-section.cjs`. Do NOT hand-write the `.cjs`; it is emitted. Tests
  * `require()` the built artifact; `pretest` runs `build:lib`.
  *
  * Pure and dependency-free.